I am a half hour in to a one hour break in of this set I got 2 days ago. So far, so good. Runs like a champ on my O31 Lionel tubular with a PW ZW for power. I had some trepidation given the above comments. I did the lube thing and let it sit upside down for 2 days.
I had trouble early on with a PS 1 Burlington Zephyr by MTH. Ended up taking the rear motor out completely. Runs fine 15 years in. I love that set!
To those experiencing difficulty with the Aerotrain, either send it back or take it to an authorized MTH station for repair. I myself have had it with poor QC from the PRC.